a. Field of the Invention
The present invention relates to a new method for identifying algae in water samples and apparatus for use in that method.
b. Description of the Prior Art
The importance of algae as a measure of water quality has been recognized by C. M. Palmer, 1957, Algae as biological indications of pollution, Biol. of Water Poll. Trans. Seminar: Biol. Problems of Water Pollution, April 1956 Robt. A. Taft, San. Eng. Center, Cincinnati(Ohio), pp 60-69, and V. Sladacek, System of water quality from the biological point of view, Arch. Hydrobiol. Beiheft 7, pp. 1-218. However the application of that approach has been limited by the time and expertise needed to identify and count samples of a heterogeneous cell suspension of some 100 to 400 cells per sample by light microscopy. In addition this approach does not allow to obtain detailed information about the various species in the sample to the extent envisaged by the invention.
Flow cytometry has been used in recent years for studying mammalian cells. The principle of the flow cytometer is that cells are suspended in a liquid stream, whereupon this stream is passed through a laser beam. Light signals, providing information about cell size, structure and chemical composition are emitted from each cell and can be measured. Using measurements of the binding of fluorescent dyes after fixation of the cells, and thus killing the cells, and the light scattering of these cells, biologists have been able to measure various biological properties and to differentiate among functional populations of cells. (See M. R. Melamed, P. F. Mullaney and M. L. Mendelsohn, Flow Cytometry and Sorting, 1979, pp. 1-9 and 11-37, John Wiley & Sons, New York).